This invention relates to apparatus for decreasing stresses and pressure generated to a person's lumbosacral spine while sitting or lying supine, prone or on the side, so as to enable the person sit or to rest with more comfort and minimize aches, pains and stiffness produced by poor sitting or sleeping posture.
For an understanding of the problems with which the present invention is concerned, the anatomy of the lower back and how it relates to posture and the pelvic force couple is of relevance. The pelvic force couple is a dynamic relationship between certain parts of the body and the forces which act upon these parts. The parts of the body making up the spinal column include; vertebrae, i.e. the bony components of the spinal column which permit and limit motion, protect the spinal cord, and support the body in an upright position; discs, i.e. tough, fibrous outer tissues (annulus fibrosis) with soft, jelly-like centers (nucleus pulposus) which act as a cushion between the vertebrae; nerves which communicate feelings and control the muscles; ligaments, i.e. tough, semi-elastic tissues which help to hold the vertebrae together and reinforce the strength of the back; and muscles, i.e. elastic contractable tissues which provide power for motive force and support for the back.
Forces which act upon the back are; the actions of muscles, and the actions of gravity. When these forces operate independently any of the following actions may result. Operation of the back extensor muscles alone may tilt the pelvis forward, increasing the lordotic curve in the lower back. Operation of the quadriceps and hip flexor muscles may also tilt the pelvis forward. Operation of the abdominal muscles may tilt the pelvis backwards decreasing the lordosis in the lower back. Operation of the gluteals and hamstrings may also tilt the pelvis backward, while the force of gravity tends to tilt the pelvis forward. If one or more of the above forces become unbalanced, this may cause problems in the operation of the pelvic force couple. The forces may for example become unbalanced from lack of muscle strength and flexibility, the aging process, wear and tear of degeneration, misuse, such as poor posture and poor body mechanics, or trauma such as torn ligaments, muscle strain, ruptured discs, or damage from disease. With the forces out of balance, a person will be more prone to injury and wear on the back while, if the forces are in balance and the pelvic force couple functions properly, a person will have good muscle support and flexibility, a slight curve in the lower back, and good alignment of the vertebrae and discs with minimal stress and pressure.
The back is affected by every position a person assumes, sitting, stooping, standing, or lying down. When performing daily activities or sitting or sleeping with poor posture a person increases the stress and pressure generated to the lumbosacral spine. This may increase the body's degenerative process, create inflammation, stiffness, pain and/or muscle spasm and disfunction.
The correct anatomical position of the lumbosacral spine is a slight lordosis. Any variation from this position increases the stress and pressure in the lower back. A number of activities during the day, as well as sitting or sleeping postures may cause the lumbosacral area to bow out (extremely flat back) or bow in (extreme lordosis). With proper education and support, the lower back can be maintained in a correct anatomical position. Excessive lordosis is generally due to one or more of the following factors, namely, weak abdominal muscles, overweight, or lazy or incorrect posture. When the lower back is put into excessive lordosis the rear joints in the back are compressed causing an increased wear and tear process and possible inflammation, stiffness and pain/spasm cycle, the hole where the nerve comes out may also narrow, causing pressure and irritation to the nerve root, and a shearing force may be placed on the discs causing the fibers of the discs to wear. When the back is extremely flat (bowed out) the compressive forces may cause a shearing force on a disc, with a similar effect to increased lordosis. Bowing out will stretch the posterior wall of a disc, increase intradiscal pressure and place posterior ligament and muscles in a stretched position.
It is evident from the foregoing that poor posture both during daytime activities, sitting and while lying down or sleeping can have deleterious effects on the back. The present invention is directed toward providing apparatus which can be used while sitting or lying down to provide a person with improved support for the lumbosacral spine reducing stress and promoting proper posture.